Increment variable value by 1 ( shell programming)

Question

I am a beginner to shell programming and it sounds like a very stupid question but i cant seem to be able to increase the variable value by 1. I have looked at tutorial but

Answer 1

These are the methods I know:

ichramm@NOTPARALLEL ~$ i=10; echo $i;
10
ichramm@NOTPARALLEL ~$ ((i+=1)); echo $i;
11
ichramm@NOTPARALLEL ~$ ((i=i+1)); echo $i;
12
ichramm@NOTPARALLEL ~$ i=`expr $i + 1`; echo $i;
13

Note the spaces in the last example, also note that's the only one that uses $i.